Ikeda Yaemon is the 18th head of the Ikeda Clan, as well as an adoptive brother of Ikeda Asaemon. As a child, Yaemon desired to be the next head of the Ikeda Clan. He tried to prove himself worthy of the title by killing several prisoners, claiming that he had used "Kimoarai" (Soul Cleansing) on them. Upon seeing this, his father tried to punish him, but was stopped by Asaemon. This incident had led to the title "17th Ikeda Yaemon" being given to her instead of him. In his last moment, Yaemon killed the Hitotsubashi guards to let his sister escape, believing that she would clean the clan's name. As a consequence for his action, he was beheaded by Hitotsubashi Nobu Nobu. His body was thrown to the river, and could not be found by the Shinsengumi. (Source: Gintama Wikia)